NoQuarter

It isn't a question as to whether the stock IC is good enough at stock pressures and temps. It is about when we are running 13-17PSI. We have much higher temps and we have pressure drop/back pressure in the intercooler to deal with. The 335 IC is know to have a 2PSI pressure drop which means the turbos are pushing out 2 more PSI than what the engine gets. Is the drop the same or progressive as we push even more air volume through it? Because ours is so much smaller, it is worth wondering if our pressure drop is even worse and how much do we really lower our higher temps?

mazekid15

I can agree that the stock exhaust is restricting, but getting downpipes is not pointless on stock exhaust. I am running 15PSI on a Vishnu PROcede Map with catless downpipes, and after the retune it is SIGNIFICANTLY faster.

Ill post a video and you'll see how hard it pulls. My 40-100 is ridiculous now. If I can get a intercooler I'd be running SAFER but for the $$ I'd rather just behave when its hot out and have fun when its COLD in the northeast.

I would really like to do an exhaust on the 535xi. Theres a kid who has a Billyboat exhaust and I am waiting to hear the video of how it sounds. The fact is exhaust will give 20HP more THATS IT, big deal.

From a sleeper standpoint, I'd prob rather just have the DOWNPIPES and tune and a FMIC and call it a day.

I raced my friends 08 550i yesterday and DESTROYED it. With just a tune I won slightly, now I just annihilated him from all gears including 100+ ( also a 09 Audi S5 bus lengths)

Persian_535i

Of course there will be gains with a stock downpipe vs a aftermarket downpipe regardless of stock exhaust aftermarket exhaust, that isn't the argument. The argument is that the gains will be minimal due to the air restriction of the size of the stock exhaust. Only when you install a 3" aftermarket exhaust to match the downpipes will you feel the full effects of the downpipes.

mazekid15

Well which ones do I get??? LOL

B&B? or RPI? only options. Cherry bomb i heard it sounds OKAY at best. Your taking a 60-70k car and making it sound like a rattlebox. I need a clean exhaust like a Eisemann on a M5 or Magnaflow on the 545.

I heard this brief sound clip but not sure if this is convincing enough.

aoschadlin

Now overall I'm confused.

I'm assuming the further performance increase is due to the fact that the secondary cats are being removed as we can see in the RPi GT exhaust? http://www.beastpower.com/p/bmw/rpi-gt/RP-BE5-60-35-EX

Makes sense.

But if we look at the Billy Boat cat back exhaust we see that it's only from the secondary cat back, you actually have to cut and rejoin the exhaust. But it's also improving the performance by approximately the same amount. But it still has a section of stock exhaust fitted. http://www.modbargains.com/BB-E60-535i-Exhaust.htm

Like I said, I'm confused.

Is it all a marketing ploy?